(1) Field of the Invention
This invention relates to radiation tomography apparatus for smaller animals for taking a tomography image of a smaller animal as a research subject. More particularly, this invention relates to radiation tomography apparatus for smaller animals for imaging two or more small animals at one time.
(2) Description of the Related Art
One example of apparatus for imaging a smaller animal as a research subject includes radiation tomography apparatus for smaller animals. This apparatus allows generation of a tomography image of a smaller animal. An experimenter can recognize an internal structure of the small animal referring to the image. See, for example, Patent Literature 1.
Description will be given of a conventional configuration of such radiation tomography apparatus for smaller animals. As shown in FIG. 10, the conventional apparatus includes a gantry 51 having an opening. The gantry 51 includes inside thereof a radiation source 53 for emitting radiation and a radiation detector 54 for detecting radiation. The radiation source 53 and the radiation detector 54 are placed as to interpose the opening of the gantry 51, and allow rotation about the opening with a relative position thereof being maintained. A smaller animal as a subject is placed inside the opening.
Description will be given of operations of the conventional radiation tomography apparatus for smaller animals. For acquiring a tomography image of a subject with use of the conventional apparatus, the subject is firstly inserted into the opening of the gantry 51. Then, imaging is performed two or more times while the radiation source 53 and the radiation detector 54 rotate about the subject. The acquired fluoroscopic images each contain images of the subject taken in different directions. These fluoroscopic images are constructed, whereby a tomography image of the subject is to be generated.
The results obtained typically have some variations due to individual differences and errors in measurement of smaller animals in physiological experiments. Accordingly, in the experiments with smaller animals, similar experiments are conducted to two or more smaller animals for obtaining experimental results in consideration of result variations. Thus, imaging with the radiation tomography apparatus for smaller animals is usually conducted for two or more smaller animals. In other words, one experiment is conducted through repeated imaging for every smaller animal.
Here, tomography apparatus has been invented that allows imaging of two or more smaller animals at one time. This will improve efficiency in experimental procedures.    [Patent Literature 1] WO 2007/141831
The conventional configuration, however, has the following problem. That is, the conventional configuration may obtain only a tomography image having difficulties with diagnosis. With the conventional apparatus, an image is to be obtained having sectional images of two or more smaller animals contained in a filed of view thereof. The sectional images of smaller animals contained in the image are similar to one another. Thus, it is difficult to determine correspondence between a sectional image and the subject individually.
As above, in the conventional tomography apparatus, an experimenter has to study a portion in the tomography image individually where each image of the smaller animals used in the experiment is contained at every generation of the tomography image. When an experimenter mistakes a subject during such operation and diagnoses a tomography image of the mistaken subject, a result different from an actual phenomenon may possibly be obtained. Accordingly, a design is needed for clearly distinguishing two or more sectional images of the smaller animal contained in the tomography image.